linux-kernel - Re: [PATCH 0/5] drm/etnaviv: Ignore MC bit when checking for runtime suspend

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Date:   Tue, 03 Mar 2020 12:55:04 +0100
From:   Lucas Stach <l.stach@...gutronix.de>
To:     Guido Günther <agx@...xcpu.org>,
        Russell King <linux+etnaviv@...linux.org.uk>,
        Christian Gmeiner <christian.gmeiner@...il.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, etnaviv@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/5] drm/etnaviv: Ignore MC bit when checking for
 runtime suspend

On Mo, 2020-03-02 at 20:13 +0100, Guido Günther wrote:
> At least GC7000 fails to enter runtime suspend for long periods of time since
> the MC becomes busy again even when the FE is idle. The rest of the series
> makes detecting similar issues easier to debug in the future by checking
> all known bits in debugfs and also warning in the EBUSY case.

Thanks, series applied to etnaviv/next.

> Tested on GC7000 with a reduced runtime delay of 50ms. Patches are
> against next-20200226.

I've already wondered if 200ms is too long, 50ms sounds more
reasonable. Do you have any numbers on the power draw on the i.MX8M
with idle GPU, vs. being fully power gated? 

Regards,
Lucas

> Thanks to Lucas Stach for pointing me in the right direction.
> 
> Guido Günther (5):
>   drm/etnaviv: Fix typo in comment
>   drm/etnaviv: Update idle bits
>   drm/etnaviv: Consider all kwnown idle bits in debugfs
>   drm/etnaviv: Ignore MC when checking runtime suspend idleness
>   drm/etnaviv: Warn when GPU doesn't idle fast enough
> 
>  drivers/gpu/drm/etnaviv/etnaviv_gpu.c  | 26 ++++++++++++++++++++++----
>  drivers/gpu/drm/etnaviv/state_hi.xml.h |  7 +++++++
>  2 files changed, 29 insertions(+), 4 deletions(-)
>